Papillomaviruses are small DNA viruses that infect a number of animal species. Over 60 different types of human papillomavirus (HPV) have been identified, which infect a variety of body locations and are responsible for common skin warts, laryngeal papillomas, genital warts and other wart-like lesions. Genital HPV infections are particularly common; a number of HPV types, but most frequently types 6, 11, 16 and 18, infect the genital tract in both men and women. In women, HPVs infect various portions of the genital tract including the cervix.
Genital HPVs are clearly a significant clinical problem. A 2010 study (HPV Infection and Transmission in Couples through Heterosexual activity) found that more than half (56%) of young adults in new sexual relationships were infected with HPV. Of those, nearly half (44%) were infected with an HPV type that causes cancer. Further, the World Health Organization estimates that around 530,000 women are diagnosed with cervical cancer and 275,128 die from the disease annually, rating the disease as the second most common cancer among 15 to 44 year-old women.